In Situ Diagnosis of Multi-site Wire Bonding Failures for Multichip IGBT Power Modules Based on Crosstalk Voltage

The online detection of aging bond wires is key to the health status awareness of smart power converters. In this paper, a new health precursor of the gate voltage undershoot VGE(pk) of the complementary switch in the half-bridge structure is proposed. It can be used to identify and distinguish multi-site bonding wire failures for both insulated gate bipolar transistors (IGBTs) and freewheeling diodes (FWDs) in multichip IGBT modules. A theoretical analysis is conducted to derive this novel precursor, which is then verified by experimental results. Then, a dedicated read-out circuit is designed for the data acquisition front end that can be integrated into gate drivers for in-situ monitoring. Finally, the effectiveness of this method is evaluated under changing operating conditions including the DC-bus voltage, the load current, and the junction temperature. The effects of their fluctuations are studied and quantified, with corresponding calibration relationships provided to improve precursor accuracy

Weighted multi-error information entropy based you only look once network for underwater object detection

Underwater object detection is considered as one of the most challenging issues in computer vision. In this paper, a weighted multi-error information entropy based YOLO (You Only Look Once) network is proposed to address underwater illumination noise affecting the detection accuracy. First, underwater illumination is essentially structural and non-uniform, and it is modeled as an independent and piecewise identical distribution, which is a generic noise model to describe the complex underwater illuminating environment and accommodates the traditional Gaussian distribution as a special case. Second, assisted by the proposed illumination noise model, a minimum weighted error entropy criterion, which is an information-theoretic learning method, is introduced into the loss function of YOLO network, and then the network parameters are trained and optimized to improve the detection performance. Furthermore, a multi-error processing strategy is simultaneously used to handle vector errors during information back-propagation in order to accelerate convergence. Experiments on underwater object detection datasets including URPC2018, URPC2019 and Enhanced dataset, show the proposed weighted multi-error information entropy based YOLOv8 network gets mean average precision (MAP) of 88.7%, 91.8% and 96.7% respectively, and average frames per second (FPS) of 116.6. These two evaluation metrics are better than the baseline YOLOv8 and the existing advanced non-YOLO approaches by at least 5.2% and 5.3% respectively. The results verify the effectiveness and superiority of the proposed network for underwater object detection in complex underwater environment.</p

1,5-Naphthyl-linked bis(imino)pyridines as binucleating scaffolds for dicobalt ethylene oligo-/polymerization catalysts: exploring temperature and steric effects.

Six examples of dinuclear bis(imino)pyridine-cobalt(ii) complexes, [1,5-{2-(CMe[double bond, length as m-dash]N)-6-(CMe[double bond, length as m-dash]N(2,6-R12-4-R2-C6H2))C5H3N}2(C10H6)]Co2Cl4 (R1 = Me, R2 = H Co1; R1 = Et, R2 = H Co2; R1 = iPr, R2 = H Co3; R1 = Me, R2 = Me Co4; R1 = Et, R2 = Me Co5; R1 = CHPh2, R2 = Me Co6), have been prepared from the corresponding bis(tridentate) compartmental ligands (L1-L6) in reasonable yields. The molecular structures of Co3 and Co5 revealed two N,N,N-cobalt dichloride units to adopt anti-positions about the 1,5-naphthyl linking unit, with each cobalt center exhibiting a distorted trigonal bipyramidal geometry. On activation with either MAO or MMAO, Co1-Co6 were shown to promote both polymerization and oligomerization of ethylene with high overall activities (up to 1.03 × 107 gPE per·mol(Co) per·h for Co1/MAO at 70 °C). Curiously, on increasing the reaction temperature a larger proportion of polymer was noted, while at lower temperature an enhanced selectivity for oligomer was seen. In general, the oligomeric products displayed Schulz-Flory distributions with high selectivities for α-olefins (>99%). On the other hand, the highly linear polymers displayed narrow dispersities and comprised both fully saturated and unsaturated chain ends with the vinyl content (-CH[double bond, length as m-dash]CH2) found to rise with the reaction temperature. By modulating the steric hindrance exerted by the ortho-R1 substituents in the precatalyst, polyethylenes displaying a remarkably broad range of molecular weights could be obtained [from 4.52 kg mol-1 (R1 = Me) to 246.7 kg mol-1 (R1 = CHPh2)]

gem-Dimethyl-substituted bis(imino)dihydroquinolines as thermally stable supports for highly active cobalt catalysts that produce linear PE waxes.

Six types of 2,8-bis(imino)-7,7-dimethyl-5,6-dihydroquinoline, 2-(ArN[double bond, length as m-dash]CMe)-8-(ArN)-7,7-Me2C9H6N (Ar = 2,6-Me2C6H3 L1, 2,6-Et2C6H3 L2, 2,6-iPr2C6H3 L3, 2,4,6-Me3C6H2 L4, 2,6-Et2-4-MeC6H2 L5, 2,4,6-tBu3C6H3 L6), distinguishable by their steric and electronic profile, are described that can readily undergo complexation with cobaltous chloride to form their corresponding LCoCl2 chelates, Co1-Co6. The molecular structures of Co2 and Co3 reveal square pyramidal geometries with ring puckering a feature of the gem-dimethyl section of their unsymmetrical N,N,N'-ligands. On activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all the cobalt complexes exhibited exceptionally high activities for ethylene polymerization with levels reaching up to 1.19 × 107 g PE per mol (Co) per h for mesityl-containing Co4. Significantly, these catalysts exhibited good thermal stability by displaying their optimal performance at temperatures up to 70 °C whilst also maintaining appreciable catalytic lifetimes. With the exception of that obtained using the most sterically hindered Co6 (2,4,6-t-butyl), the polyethylenes are of low molecular weight (Mw ≤16.0 kg mol-1) and of narrow dispersity (Mw/Mn ≤3.4). Moreover, end-group analysis of these highly linear polymer waxes reveals evidence for unsaturated as well as various levels of fully saturated materials highlighting the role of both β-H elimination and chain transfer to aluminum as termination pathways

Enhancing thermostability of iron ethylene polymerization catalysts through N,N,N-chelation of doubly fused ,-bis(arylimino)-2,3:5,6-bis(hexamethylene)pyridines

The ferrous chloride complexes, [2,3:5,6-{C5H10C(NAr)}2C5HN]FeCl2 (Ar = 2,6-Me2Ph Fe1, 2,6-Et2Ph Fe2, 2,6-i-Pr2Ph Fe3, 2,4,6-Me3Ph Fe4, and 2,6-Et2-4-MePh Fe5), each bearing a N,N,N-ligand incorporating two partially saturated fused eight-membered rings, have been synthesized by the one-pot template reaction of α,α′-dioxo-2,3:5,6-bis(hexamethylene)pyridine, iron(II) chloride tetrahydrate and the corresponding aniline in acetic acid. The structures of Fe3 and its oxidized diferric derivative, [2,3:5,6-{C5H10C(N(2,6-i-Pr2Ph))}2C5HN]FeCl(μ-O)FeCl3 (Fe3′), revealed square pyramidal geometries with either a chloride or an oxo ligand filling the apical sites, respectively. On treatment with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all precatalysts displayed good thermostability (optimal operating temperatures: 50–80 °C) and moreover delivered exceptionally high activities for ethylene polymerization [up to 12.23 × 106 g (PE) mol−1 (Fe) h−1] producing highly linear polyethylene of high molecular weight (Mw up to 62.5 kg mol−1 even at 80 °C). The catalytic activities fall in the order, Fe1 > Fe4 > Fe2 > Fe5 > Fe3 (MMAO or MAO), with both steric and electronic factors influential; iron(III)-containing Fe3′ was less active. Distinct chain termination processes for the polymerizations have been identified through end-group analysis with both β-H elimination and chain transfer to aluminum operative with MMAO, while only transfer to aluminum has been detectable with MAO. Notably with MMAO, the different rates of these termination processes manifests itself in bimodal molecular weight distributions for the polyethylenes

IGBT Junction Temperature Estimation Using a Dynamic TSEP Independent of Wire Bonding Faults

Despite that many temperature-sensitive electrical parameters (TSEPs) have been discovered for the online estimation of the junction temperature of IGBT devices, their wide adoption in the field is yet to come. This is because they are most susceptible to both the aging status and operating points of IGBTs, which can result in inaccurate results if not attended. In this study, a novel dynamic TSEP, the gate voltage undershoot VGE(np) of the complementary IGBT switch, is proposed. It is based on the crosstalk effect and measured during the turn-off switching transition of the controlled IGBT switch for its temperature estimation. Its monotonic temperature dependence has been identified with implications for the changing load current and bus voltage, which are experimentally verified using a 1200 V/450 A IGBT module. The theoretical analysis and experimental results also show that VGE(np) is independent of bond wire failures while providing comparatively high relative sensitivity. The MMC power equivalent experimental results are given to verify the feasibility of the proposed method in commercial engineering applications. Finally, the multivariate linear regression method is used to improve the ability to estimate the IGBT's temperature by accounting for the operating point

CH(phenol)-Bridged Bis(imino)pyridines as Compartmental Supports for Diiron Precatalysts for Ethylene Polymerization: Exploring Cooperative Effects on Performance

A family of six CH(phenol)-bridged bimetallic bis(imino)pyridine-iron(II) chlorides, CH(C6H4-4-OH){2′-(4-C6H2-2,6-(R1)2N═CMe)-6′-(2″,6″-(R2)2-4-(R3)C6H2N═CMe)C5H3N}2Fe2Cl4 [R1 = R2 = Me, R3 = H, Fe1; R1 = R2 = Et, R3 = H, Fe2; R1 = Me, R2 = Et, R3 = H, Fe3; R1 = Me, R2 = i-Pr, R3 = H, Fe4; R1 = R2 = R3 = Me, Fe5; R1 = R2 = Et, R3 = Me, Fe6], has been synthesized by the reaction of the corresponding compartmental ligand with 2 equiv of FeCl2·4H2O. The molecular structure of Fe6 reveals an intramolecular Fe···Fe separation of 10.152 Å, with pairs of Fe6 assembling through intermolecular OH···Cl hydrogen bonding interactions. On activation with MAO or MMAO, Fe1–Fe6 exhibited both good thermal stability and very high activity for ethylene polymerization with the least sterically bulky compound, Fe1, being the standout performer (up to 2.43 × 107 g·mol–1(Fe)·h–1 at 60 °C). Notably, Fe1/MAO showed almost double the activity of a structurally related mononuclear catalyst while the resultant polyethylene exhibited much higher molecular weight. In general, the polymeric materials are highly linear and have a tendency to display bimodal distributions that is influenced by the amount of cocatalyst employed. End-group analysis of the polymers generated using MMAO activation reveals chain ends composed of vinyl and saturated groups (propyl and isobutyl), while with MAO, a preference for propyl end groups is observed

Mutation in clpC1 encoding an ATP-dependent ATPase involved in protein degradation is associated with pyrazinamide resistance in Mycobacterium tuberculosis

No description supplie

Supplementary information files for Investigation of solution-based synthesis of non-toxic perovskite materials using Mg, Ca, Mn, Fe, Cu, and Zn as the B-site cation for photovoltaic applications

Supplementary files for article Investigation of solution-based synthesis of non-toxic perovskite materials using Mg, Ca, Mn, Fe, Cu, and Zn as the B-site cation for photovoltaic applications  High-efficiency perovskite solar cells are reliant on lead-based materials, which causes toxicity issues for large-scale implementation. Current alternatives can contain similarly environmentally dangerous chemicals such as tin halide compounds. Computational studies have suggested a large array of different potential B-site metal cations that could produce suitable perovskite materials. In this work, simple, solution synthesis of 24 candidate materials is attempted with a focus on the environmental safety of the starting compounds. Of these 24 materials, 10 formed a new material from XRD characterisation, and 1 of the resulting films produces a material with an observable band-gap in UV/vis. This material, a combination of potassium bromide and copper bromide, failed to produce a solar cell of any notable efficiency. This work demonstrates that completely environmentally benign perovskite materials may require more energy-intensive synthesis such as solid-state methods, removing the benefits of simple, solution processing evident in lead-halide perovskite solar cells. </p

Phylogenetic and Pathotypic Characterization of a Newcastle Disease Virus Strain Isolated from Ducks and Pigeons in Hubei, China

<div><p>ABSTRACT Newcastle disease is a highly contagious disease responsible for major outbreaks and considerable economic losses in the poultry industry in China. There is still little information available regarding gene characterization of the NDV, especially in ducks and pigeons. Therefore, the aim of this study was to investigate NDV isolated from ducks and pigeons in Hubei, China. In this study, three NDVs from ducks and pigeons were isolated between 2013 and 2015.The fusion protein (F) gene of the NDV isolates was sequenced and phylogenetically analyzed. The clinical signs and gross histopathological lesions were examined. Phylogenetic analysis of these strains indicated that all the sequences are classified as genotype II. The isolates shared a 112 G-R-Q-G-R-L 117motif at the F protein cleavage site, indicating that these three isolates strains are lentogenic. Necropsy and histopathology showed the typical pathological changes. It was concluded that commercial ducks and pigeons in Hubei province carry lentogenic NDV strains with regular genetic divergence, indicating that these species may act as the main reservoirs of NDV in poultry. Therefore, strategies and surveillance should be undertaken to reduce the risk of ND outbreaks.</p></div